Conventional fracturing or “frac” valves typically include a cylindrical housing that may be threaded into and form a part of a production liner. The housing defines an axial bore through which frac fluids and other well fluids may flow. Ports are provided in the housing that may be opened by actuating a sliding sleeve. Once the ports are opened, fluids are able to flow through the ports and fracture a formation in the vicinity of the valve.
The sliding sleeves in such valves are typically actuated either by creating hydraulic pressure behind the sleeve or by dropping a ball on a ball seat connected to the sleeve. Some multi-stage fracking systems use both hydraulic pressure and balls. More particularly, some systems include a hydraulically-actuated sliding sleeve valve which, when the liner is run into the well, is located near the bottom of the wellbore in the first fracture zone.
Such valves have been used successfully in many applications. However, in some hydraulically-actuated valves, relatively small chambers are formed therein that are in communication with the interior bore of the tool. These chambers can thus become fouled with debris from the fluid in the bore, potentially impacting the reliability of the valve actuation.